Hearing aids are used to supply hearing-impaired persons with suitable auditory signals. The auditory signals generally consist of acoustic signals, which are recorded by the hearing aid, pass through a transmission function therein and are output by way of a loudspeaker, a so-called receiver. The transmission function is converted in a signal processing electronics system, which effects inter alia amplification in certain acoustic frequency ranges. Depending on the type and extent of the hearing damage of the respective hearing aid wearer, different frequency ranges result for the amplification, which however lie within the frequency range of human hearing, as well as different degrees of amplification.
To treat hearing-impaired persons, in addition to hearing aids, devices for tinnitus therapy are also used, which can be largely similar to hearing aids. In contrast to hearing aids, devices for tinnitus therapy frequently generate acoustic output signals, which are independent of acoustic signals recorded by the device. For instance, noises for reducing or covering tinnitus interference noises are generated. The term “hearing aid” is to be understood below both as hearing aids as well as tinnitus therapy devices.
Hearing aids are developed with the smallest possible device volume. A small device volume increases the wearing comfort on the one hand, and also reduces the conspicuousness on the other hand, which is frequently perceived by hearing aid wearers as unpleasant. A small installation size also plays a special role in ITE devices (in-the-ear) and CiC devices (completely-in-the-canal), which are partially or completely inserted into the auditory canal of the hearing aid wearer.